Power supplying device

Abstract

A power supplying device includes: an output transformer including first and second output coils for generating first intermediate voltages from an input voltage; a voltage adjusting transformer including primary and secondary coils; a first rectifying-and-filtering circuit connected to the first output coil for generating a first output voltage from the first intermediate voltage obtained from the first output coil; the primary coil being connected in parallel to the first output coil, the secondary coil being connected in series to the second output coil and being coupled to the primary coil for generating a second intermediate voltage from the first intermediate voltage obtained from the first output coil; and a second rectifying-and-filtering circuit connected to the secondary coil for generating a second output voltage from a combined voltage combining the second intermediate voltage obtained from the secondary coil with the first intermediate voltage obtained from the second output coil.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority of Taiwanese Application No. 097100561, filed on Jan. 7, 2008.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention relates to a power supplying device, more particularly to a power supplying device capable of providing adjustable output voltages.[0004]2. Description of the Related Art[0005]Since internal components of most electronic devices, such as televisions, monitors, stereo systems, computers, etc., require different direct-current (DC) voltages, a switching power supplying device capable of converting a DC input voltage into various DC output voltages is used in the electronic devices so as to supply the various DC output voltages respectively to the internal components of the electronic devices.[0006]However, differences are usually present between the actual DC output voltages and the voltages required by the internal components due to an excessively large induced voltage a...

AI Technical Summary

Benefits of technology

[0009]Therefore, an object of the present invention is to provide a power supplying device that has a relatively high power converting efficiency, that has a relatively simple circuitry, that is relatively low cost, and that provides adjustable output voltages.

Problems solved by technology

However, differences are usually present between the actual DC output voltages and the voltages required by the internal components due to an excessively large induced voltage at each output coil of an output transformer used in a conventional switching power supplying device.

However, the DC-DC converter not only involves complicated circuitry and is costly, but radiation problems such as radio frequency interference (RFI) are also easily generated therein.

On the other hand, the linear regulator can only be used for reducing voltages, and power converting efficiency thereof is poor, especially when a difference between the input voltage and the output voltage is large.

In addition, since voltage level of the input voltage exceeding the output voltage is consumed in the form of heat energy, this voltage level cannot be applied to an output circuit, and an external heat-dissipating mechanism is even required to accelerate heat dissipation.

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